On May 8, 2013, the US Environmental Protection Agency (EPA)
Office of Pesticide Programs, Antimicrobial Division (AD), released
its long-awaited final rule regarding data requirements for
antimicrobial pesticides.1 The new requirements
(Subpart W of 40 CFR Part 158 or Part 158W) update and replace Part
161 of Title 40 of the Code of Federal Regulations with the goal of
"providing an up-to-date scientific framework for identifying
and assessing the risks of antimicrobial pesticides sold or
distributed in the United States."2
This final rule represents a fundamental change in the way
antimicrobial products will be reviewed in the US. The rule
sets forth significant new data requirements for antimicrobial
products, including food contact materials, antifoulant coatings
and paints, and wood preservatives. The new requirements will
likely result in significantly increased data costs for many types
of antimicrobial products, and may increase the time required to
complete the registration process.
The EPA codified 11 new data requirements in this final rule.
One such major new requirement involves how AD will handle
"down the drain uses" where the "EPA intends to
conduct an assessment of the potential impact of the antimicrobial
chemical on the microorganisms in the biological treatment
processes of a [waste water treatment plant] and the potential for
the antimicrobial chemical to pass through the [waste water
treatment plant] in effluent."3 Another major
new requirement is the need to determine the nature and magnitude
of antimicrobial pesticide residues on surfaces as a "more
definitive trigger" for subsequent migration studies to
determine rate and amount of materials being released from a
In the preamble to the rule, the EPA has reiterated its
expansive interpretation of the its authority over food use
products, indicating that the EPA will re-review and approve many
of the same chemicals and uses reviewed by the US Food and Drug
Administration (FDA). Thus food use products may be subject
to extensive additional data requirements.
The EPA views the 158W rule as a "launching pad" for
the use of "21st Century toxicology and integrated testing
strategies" that may ultimately help reduce animal use and
cost associated with toxicity testing. The basic strategy is
to "maximize use of existing data from similar compounds,
including information from new in silico and in vitro predictive
models and exposure modeling to target in vivo toxicity testing
that is needed to assess and manage risks," including the use
of quantitative structure-activity relationships (QSAR) and
thresholds of toxicological concern (TTC).4 To
evaluate the efficacy of this new approach to safety testing, the
EPA will use "[d]ata from improved biomarkers of exposure and
biological outcomes from population-based
The rule is effective July 8, 2013. However, the EPA
recognizes that registrants may not have all the newly-required
data by that date, and therefore may "extend up to two years
post-promulgation for situations in which a more time-intensive new
study is missing."6
There will be several additional guidance documents issued over
the next several months as the EPA works to implement the new 158W
data requirements. For example, the EPA intends to issue a
"toxicity data requirement" guidance document on
performing weight-of-evidence evaluation to determine overall
toxicity data needs as well as evaluating waiver justifications. In
addition, as mentioned in the final rule (78 FR at 26940), the EPA
will prepare an Antimicrobial Use Site Index "to provide
additional information about ... use patterns."
Registrants will want to keep abreast of these Part 158W
implementation actions over the next few months, as the
forth-coming guidance will be critical to understanding the 158W
requirements and risk assessment process.
In sum, the new Part 158 Subpart W represents a sea change in
how antimicrobial products will be reviewed in the US.
Companies seeking new registrations, amending existing
registrations, or undergoing registration review for antimicrobial
products will need to evaluate these data requirements to
understand the potential implications for their products. In
some case, consultation with the EPA may be necessary to fully
understand the requirements applicable to a particular product.
1 See 78 Federal Register 26936;Data Requirements for Antimicrobial Pesticides; Final Rule;
May 8, 2013.
2 Ibid, at 26936
3 Ibid, at 26938
4 Ibid, at 26938
5 Ibid, at 26939
6 Ibid, at 26792
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On May 27, 2015, the United States Environmental Protection Agency and the United States Army Corps of Engineers issued their highly anticipated final revision to the definition of "waters of the United States."